The program encompasses over 60 inter-related projects under the following general headings: Section A - Microbiologically defined inbred mice and hamsters - 4 projects. Section B - Gnotobiotic isolation systems for immune deficient infants - 4 projects. Section C - Immunology and attempted reconstitution of a gnotobiotic immune deficient infant - 7 projects. Section D - Immunological enhancement and tolerance - 4 projects. Section E - Thymosin studies - 3 projects. Section F - Antilymphocyte, antimacrophage and anti bone marrow serum studies - 7 projects. Section G - Viral oncology and immunology - 24 projects. Section H - Tumor immunology - 8 projects. Section I - Genetic (hybrid) resistance and leukemia - 7 projects. Section J - Substitution of bacterial lipopolysaccharide (LPS) for T-cell cooperation. In addition to projects within the Division of Experimental Biology, the program includes collaborative projects with investigators in the Department of Pediatrics, Baylor College of Medicine, and Texas Children's Hospital, and with investigators at the University of Texas M.D. Anderson Hospital and Tumor Institute, and at the University of Texas Medical Branch at Galveston.